Simulated behaviour of a vehicle with V-belt geared neutral transmission with variator slip control

Abstract

Combining both launch and reverse drive functions with the ratio change function in a geared neutral continuously variable transmission (GN-CVT), thus making a launch device like a torque converter and a drive-neutral-reverse (DNR) set obsolete, is attracting considerable attention. This paper covers the modelling and simulation of a V-belt geared neutral transmission in and around the geared neutral point. Owing to the specific nature of the geared neutral state, conventional driveline simulation models are shown to be inadequate. Experimental results are presented, allowing a more detailed description of the functional properties of the V-belt variator, especially those related to small amounts of slip between the belt and the pulleys. The measured data will be analysed to obtain grey model fitting parameters, which allow the data to be used in a simulation program based on a dynamic driveline model. It will be shown that, with a GN-CVT, stall and launch performance can be considerably better than that achieved with a driveline with a torque converter (TC).